Top and bottom loaded filter and locking mechanism

ABSTRACT

A filter element includes a bottom open end joined to a center tube opposite the top open end. The bottom open end defines a radially outer surface and a radially inner surface that is in communication with the central reservoir of the filter element. A first locking feature is disposed proximate to the bottom open end. The locking feature includes an entrance slot that is disposed on the radially inner surface of the center tube extending axially from the bottom open end. A similar or identical second locking feature is disposed proximate to the top open end.

TECHNICAL FIELD

This application is a divisional application of application Ser. No.16/799,193, filed on Feb. 24, 2020, having the same title, claimingpriority thereto and incorporating its contents herein by reference inits entirety.

TECHNICAL FIELD

The present disclosure relates generally to canister style filtersystems that employ a replaceable filter element. More specifically, thepresent disclosure relates to a filter element that includes a lockingfeature for retaining the filter element in a desired position whileproviding a seal that helps to ensure that dirty fluid is filtered bythe filtering medium of the filter element.

BACKGROUND

Liquid filter systems are known for filter various fluids such as gas,oil, diesel fuel, etc. to remove contaminants from these fluids. Indiesel engines, for example, a fuel line filter is used to separate outwater and debris from the fuel. These contaminates may accumulate in alower portion of the filter housing (may also be referred to as acanister). Typically, the center tube of the filter element providessupport for the filter media but may not always provide the desiredlocation and retention.

U.S. Pat. Application Publication No. 20060207948 to Hacker et al.discloses a fluid filter assembly including a housing, a service cover,a center tube removably secured to the service cover, and a filtercartridge removably sealed and circumscribing the center tube, and aseal arrangement. The seal arrangement is between the center tube andportions of the housing to close a drainage change to the flow of aclean fluid flow therethrough, when the fluid filter assembly isoperating to filter the fluid.

During normal operation in Hacker, the fluid filter assembly operates toallow fluid to flow into the housing through an inlet channel, throughthe filter cartridge, through openings in the center tube, and out ofthe housing through the outlet channel. Methods for servicing includeremoving a service cover from a housing to remove, together with theservice cover, a center tube, and open a drainage flow passageway fromthe housing. Next a filter cartridge is removed from the center tube,and a new filter cartridge is operably mounted on the center tube. Next,the service cover with the center tube having the new filter cartridgeis operably mounted in the housing to close the drainage flowpassageway.

In Hacker, methods of filtering will direct fluid to be filtered into ahousing having a removable and replaceable filter cartridge; then directthe fluid through a tubular region of filter media in the cartridge;then through fluid openings in a center tube; and into a clean fluidflow passageway. Example methods include preventing fluid to bypass thefilter media by removably sealing the filter cartridge to the centertube. Example methods will also include preventing fluid from flowinginto a drainage passageway by removably sealing the center tube to otherportions of the filter housing. Systems utilizing filter assembliesdescribed in Hacker include fuel systems, lube systems, and hydraulicsystems.

Hacker fails to disclose a feature on the center tube that may be usedto both position and retain the filter element in a desired positionwhile also providing a seal that forces dirty fluid to pass through thefilter medium of the filter element before exiting the filter element.

SUMMARY OF THE DISCLOSURE

A filter element that includes at least a partially annularconfiguration and that defines a longitudinal axis, a radial direction,and a circumferential direction according to an embodiment of thepresent disclosure is provided. The filter element may comprise anannular filter media defining a central passage, a center tube that isdisposed in the central passage of the annular filter media that definesa central reservoir, and the annular filter media surrounds the centertube and the central reservoir. A top open end may be joined to thecenter tube disposed along the longitudinal axis, the top open endincluding an opening allowing fluid to flow from the central reservoirto the outside of the filter element. A bottom open end may be joined tothe center tube opposite the top open end disposed along thelongitudinal axis, the bottom open end defining a radially outer surfaceand a radially inner surface that is in communication with the centralreservoir. A first locking feature may be disposed proximate to thebottom open end, the first locking feature including a first entranceslot that is disposed on the radially inner surface of the center tubeextending axially upwardly from the bottom open end, and a first rampslot extending axially upwardly and circumferentially counterclockwisefrom the first entrance slot along a first predetermined direction, thefirst ramp slot being in communication with the first entrance slot. Asecond locking feature may be disposed proximate to the top open end,the second locking feature includes a second entrance slot that isdisposed on the radially inner surface of the center tube extendingaxially downwardly from the top open end, and a second ramp slotextending axially downwardly and circumferentially clockwise from thesecond entrance slot along a second predetermined direction, the secondramp slot being in communication with the second entrance slot.

A pair of pedestals for use with a canister filter system and a filterelement according to an embodiment of the present disclosure isprovided. Each of the pair of pedestals may comprise an at leastpartially annular body defining a longitudinal axis, a radial direction,and a circumferential direction, and may include a top annular portionterminating at a top free end, and a tab extending radially from the topannular portion, the tab including a first axial surface, a bottomcircumferential surface, and a bottom ramp surface extending from thebottom circumferential surface.

A canister filter system according to an embodiment of the presentdisclosure may comprise a filter element that includes at leastpartially a cylindrical configuration and that defines a longitudinalaxis, and a radial direction. The filter element may comprise an annularfilter media defining a central passage, a center tube that is disposedin the central passage of the annular filter media that defines acentral reservoir, and the annular filter media surrounds the centertube and the central reservoir. A top open end may be joined to thecenter tube disposed along the longitudinal axis, the top open endincluding an opening allowing fluid to flow from the central reservoirto the outside of the filter element, and a bottom open end may bejoined to the center tube opposite the top open end disposed along thelongitudinal axis. A canister may be provided that includes a top openend, and a bottom closed end or a bottom open end disposed along thelongitudinal axis. A base that is configured to be attached to thecanister may also be provided, as well as a bottom pedestal including anat least partially annular body defining a longitudinal axis, a radialdirection, and a circumferential direction. The bottom pedestal mayinclude a top annular portion terminating at a top free end and defininga top diameter, a bottom annular portion defining a bottom diameter thatis greater than the top diameter, and a bottom tab extending radiallyfrom the top annular portion. The bottom pedestal may rest on the bottomclosed end of the canister, and the filter seal may be disposed belowthe tab of the bottom pedestal and around the bottom annular portionwhile contacting the canister. A top pedestal may also be provided thatcomprises a top tab, the top pedestal being operatively associated withthe base.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front sectional view of a filter assembly that includes afilter base, a canister, and a filter element including a center tubewith a locking feature according to an embodiment of the presentdisclosure, and a pedestal that is configured to mate with the lockingfeature.

FIG. 2 is a front sectional view of the bottom portion of a filterassembly similar to that of FIG. 1 with the annular filter mediaremoved, showing the mating of the pedestal with the locking feature ofthe center tube according to an embodiment of the present disclosure.

FIG. 3 is a perspective view of the filter assembly of FIG. 2illustrating how the pedestal rests or extends from the bottom of thecanister.

FIG. 4 is an enlarged perspective view of the mating of the tab of thepedestal with the locking feature of the center tube.

FIG. 5 shows the canister and pedestal shown in isolation from thefilter assembly of FIG. 3.

FIG. 6 is a bottom oriented perspective view of the filter seal showingits aperture that is configured to mate with the cylindrical or conicalsurface of the pedestal.

FIG. 7 is a perspective view of the center tube shown in isolation fromthe filter assembly of FIG. 1.

FIG. 8 is a perspective view showing conceptually how a center tube suchas the one similar in construction to the center tube of FIG. 7 may beconfigured to mate with the base at the top end and the pedestal at thebottom end of a filter assembly.

FIG. 9 is an enlarged detail view showing the mating of the locking slotof the center tube and pedestal similar to the bottom portion of FIG. 8except the pedestal is shown near the top in FIG. 9. The tab of thepedestal is shown being rotated during an assembly or locking operation.

FIG. 10 illustrates that the tab of the pedestal of FIG. 9 is smallenough to fall into the detent notch.

FIG. 11 is an enlarged detailed view showing the mating of the lockingslot of the center tube and pedestal similar to the top portion of FIG.8. The tab of the pedestal is shown to be too large to fit into thedetent notch.

FIG. 12 is a flow chart containing a method of operation or assemblyassociated with FIGS. 9 thru 10.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the disclosure,examples of which are illustrated in the accompanying drawings. Whereverpossible, the same reference numbers will be used throughout thedrawings to refer to the same or like parts. In some cases, a referencenumber will be indicated in this specification and the drawings willshow the reference number followed by a letter for example, 100 a, 100 bor a prime indicator such as 100′, 100″ etc. It is to be understood thatthe use of letters or primes immediately after a reference numberindicates that these features are similarly shaped and have similarfunction as is often the case when geometry is mirrored about a plane ofsymmetry. For ease of explanation in this specification, letters orprimes will often not be included herein but may be shown in thedrawings to indicate duplications of features discussed within thiswritten specification.

First, a filter system will now be described to give the reader theproper context for understanding how various embodiments of the presentdisclosure are used. It is to be understood that this description isgiven as exemplary and not in any limiting sense. Any embodiment of anapparatus or method described herein may be used in conjunction with anyfilter system.

Then, a filter element that may include a center tube with a lockingfeature according to various embodiments will be discussed. This featuremay be located in the bottom end of a liquid filter assembly with areusable housing (may be referred to as a canister), and it may positionthe filter element radially and axially in the canister (may also bereferred to as the housing) while also separating the clean fluid fromthe dirty fluid on different sides of the filter medium via a seal. Infuel-water separators, the positioning geometry may be configured tocreate a chamber for collecting water (i.e. a water bowl) or debris bypreventing the element from extending to the bottom of the canister.

FIG. 1 illustrates a canister filter system 100 that may use a filterelement 200, and a pedestal 300 according to various embodiments of thepresent disclosure.

The canister filter system 100 may include having a base 102 (shown tobe split up into a base adapter 102a and a filter base 102b, but couldbe one integral component), a canister 104, a pedestal 300, and a filterelement 200. The canister filter system 100 may be used to filter fluidssuch as diesel or gasoline or other liquid fuels, lubrication oil,hydraulic fluid for hydraulic power systems, transmission fluid, or evenpossibly intake air for an engine. The canister filter system 100 mayalso be used as a fuel/water separator filter. The canister filtersystem 100 with the features described herein could be adapted by thoseof ordinary skill in this art to serve many different purposes and suitmany other applications.

The base 102 includes an inlet channel 106 for fluid to enter into thecanister filter system 100, and an outlet channel 108 for fluid to exitfrom the canister filter system 100. A clip 110 is provided to attachthe canister 104 to the base 102. Other attachment structure such asthreads may be used.

The canister 104 includes a top open end 112 and a bottom open end 114as shown in FIG. 1 or a bottom closed end 116 as shown in FIGS. 2 and 3.

The filter element 200 may take many different forms to suit aparticular application. In the illustrated embodiment, the filterelement 200 is well suited for filtering fuel or lubrication oil. Thefilter element 200 may include annular filter media 202circumferentially surrounding a central reservoir 204 defined by acenter tube 206. Axial ends of annular filter media 202 are shown to besealed by end caps.

A top end cap 208 may define an axial open end of filter element 200.The top end cap 208 is termed “open” because it includes an opening 210for allowing passage of fluid.

On the other hand, the bottom end cap 212 defines an axial closed end offilter element 200. The bottom end cap 212 is termed “closed” because itprevents any fluid outside the filter element 200 adjacent the axial endof the annular filter media 202 from flowing unfiltered into center tube206.

The top end cap 208 and the bottom end cap 212 may each be joined to thecenter tube 206 via welding, adhesives, etc. Alternatively, several orall of center tube 206, the top end cap 208, and the bottom end cap 212may be constructed as unitary components. Conversely, the bottom end cap212 and/or the top end cap 208 may be separate components from thecenter tube 206, etc. Further details of the closed configuration of thebottom of the canister filter system 100 and the filter element 200 willbe discussed later herein.

In operation, fluid to be filtered enters from the inlet channel 106 andflows to the annular cavity 118 between canister 104 and the annularfilter media 202. The fluid then passes into and through filter media202, then into the center tube 206 through the perforations 214 showntherein in FIG. 1.

Then, the fluid exits center tube 206 through the top end cap 208 andopening 210 into the outlet channel 108. The sealed construction at thebottom of the filter element 200 helps to define the fluid channels intoand out of the annular filter media 202, preventing any fluid fromflowing directly to outlet channel 108 and bypassing the annular filtermedia 202. To that end, sealing features may be provided that will bediscussed in detail later herein. Moreover, it may be desirable tocreate a chamber (e.g. a water bowl in fuel-water separators, a drainreservoir, etc.) between the bottom of the filter element and the bottomof the canister. So, a positioning feature may be provided as will bediscussed later herein.

Referring now to FIGS. 1 thru 3, a canister filter system 100 accordingto various embodiments of the present disclosure that provides lockingand/or positioning feature(s) will now be discussed.

The canister filter system 100 may comprise a filter element 200 thatincludes at least partially a cylindrical configuration and that definesa longitudinal axis 216, a circumferential direction 217, and a radialdirection 218. The filter element 200 may comprise an annular filtermedia 202 defining a central passage 219 and a center tube 206 that isdisposed in the central passage 219 of the annular filter media 220 thatdefines a central reservoir 204. Thus, the annular filter media 202surrounds the center tube 206, and the central reservoir 204.

As best seen in FIG. 1, the filter element 200 may further include a topopen end 220 joined to the center tube 206 disposed along thelongitudinal axis 216. The top open end 220 includes an opening 210 thatallows fluid to flow from the central reservoir 204 to the outside ofthe filter element 200.

Similarly, the filter element 200 may include a bottom open end 222joined to the center tube 206 opposite the top open end 220 that is alsodisposed along the longitudinal axis 216. Thus the bottom open end 222allows insertion of the pedestal 300.

The canister filter system 100 may also include a canister 104 thatincludes a top open end 112 (see FIG. 1), and a bottom closed end 116(see FIGS. 2 and 3) relative to the longitudinal axis 216, and apedestal 300 that rests on the bottom closed end 114 of the canister104. This may not be the case in other embodiments of the presentdisclosure such as in FIG. 1 wherein the pedestal 300 is molded integralwith the canister 104.

Looking now at FIGS. 2 thru 5, the pedestal 300 may include an at leastpartially annular body 302 (may be completely annular with a thru-hole304 extending from end to end as best seen in FIG. 5 or not such asshown in FIG. 1) defining a longitudinal axis 306, a radial direction308, and a circumferential direction 310 (see FIG. 5, may be concentricwith the filter element once assembled).

Focusing on FIG. 5, the body 302 may include a top annular portion 312terminating at a top free end 314 (regardless of whether it is open orclosed) and may also define a top diameter 316 (i.e. top outerdiameter), and a bottom annular portion 318 defining a bottom diameter320 (i.e. bottom outer diameter) that is greater than the top diameter316.

A tab 322 may extend radially from the top annular portion 312, and afilter seal 120 may be provided that defines an aperture 122 that isconfigured to mate with the bottom annular portion 318 of the pedestal300 (see also FIG. 6).

With continued reference to FIG. 5, the pedestal 300 may rest on thebottom closed end 114 of the canister 104. The filter seal 120 may bedisposed below the tab 322 of the pedestal 300 and around the bottomannular portion 318 while contacting the canister 104.

More specifically, the canister 104 comprises an outer annular wall 124that defines an outer diameter 126 (see FIG. 1) that is greater than thebottom diameter 320 of the pedestal 300, a support wall 128 that isconfigured to support the bottom annular portion 318 of the pedestal300, and an arcuate wall 130 (other configurations are possible) thatconnects the support wall 128 to the outer annular wall 124 (see FIG.5).

As shown in FIG. 3, the filter seal 120 may contact the arcuate wall130, forming a drain reservoir 132. More particularly, the bottom openend 222 of the center tube 206 may impinge upon the filter seal 120,creating a fluid tight seal between center tube 206 and the filter seal120, and another fluid tight seal between the filter seal 120 and thearcuate wall 130 of the canister 104.

Looking at FIG. 6, a ratio of the outer diameter 136 to the thickness134 of the filter seal 120 of the filter seal may range from 10.0 to30.0, while a ratio of the outer diameter 136 to the hole diameter 137may range from 1.5 to 3.0. This geometry in addition to the elastomericcomposition of the filter seal may provide the suitable balance betweenrigidity and flexibility to allow the center tube and pedestal to beconnected while providing the water tight seals. For example, a materialof urethane having a durometer of 55 to 65 Shore A (e.g. 60 Shore A) maybe employed.

Looking at FIGS. 2 thru 4, the center tube 206 includes a locking slot224 that extends axially from the bottom open end 222 of the center tube206 an axial distance 226, and then extends circumferentially acircumferential distance 228.

Referring to FIGS. 3 and 5, the center tube 206 may define an innerdiameter 230 that is slightly greater (i.e. 0.015 of an inch to 0.030 aninch of clearance) than the top diameter 316 of the pedestal 300 that isdisposed within the inner diameter 230, and the tab 322 of the pedestal300 may be disposed in the locking slot 226, and may be configured toguide the movement of the center tube 206. This arrangement may providea positioning/centering function. Though not shown, an 0-ring or otherseal may be provided at this interface 138 to prevent fluid frombypassing the annular filter media 202 in some embodiments such as whenthe annular filter media does not extend axially past the locking slot.

As best seen in FIG. 5, the pedestal 300 may include a flared annularportion 324 (e.g. a conical shape, an arcuate shape, etc.) that connectsthe top annular portion 312 to the bottom annular portion 318. Thisfeature may be omitted in other embodiments. As best seen in FIG. 6, theradially inner surface 234 of the center tube 206 may have a matchingshaped (e.g. angled or tapered) to ease installation of the centertube/filter element onto the pedestal. This may provide guidance as thetabs enter the locking slots.

Referring once more to FIG. 5, the bottom annular portion 318 may beattached to the canister 104. For example, when the canister and thepedestal are formed by thermoplastic injection molding (e.g. using apolyruethane material, nylon material, etc.), the pedestal may beultrasonically welded to the canister, molded integrally with thecanister, snapped onto the canister, threaded onto the canister etc.Also, a protuberance may extend from the canister about which thepedestal is centered, etc. Other manufacturing methods are possibleincluding sheet metal fabrication, etc. When metal is employed, thepedestal may be attached to the canister via welding, brazing,threading, etc.

The bottom annular portion 318 may define at least one thru-slot 326that extends radially and possibly axially downwardly through the bottomannular portion 318. This may allow water or debris to exit from thecentral reservoir 204 of the center tube 206 to the drain reservoir 132(e.g. see FIG. 3).

Now, a filter element 200 that may be used with the that includes atleast a partially annular configuration (e.g. conical, cylindrical,other bodies of revolution, etc.) and that may be used with the canisterfilter system 100 just described will be discussed with reference toFIGS. 1 thru 4, and 7.

Starting with FIGS. 1 and 7, the filter element 200 may define alongitudinal axis 216, a radial direction 218, and a circumferentialdirection 217. Moreover, the filter element 200 may comprise an annularfilter media 202 defining a central passage 219.

A center tube 206 may be disposed in the central passage 219 of theannular filter media 202 that defines a central reservoir 204.Accordingly, the annular filter media 202 surrounds the center tube 206and the central reservoir 204. A top open end 220 may be joined to thecenter tube 206 that is disposed along the longitudinal axis 216. Thetop open end 220 includes an opening 210 allowing fluid to flow from thecentral reservoir 204 to the outside of the filter element 200 or viceversa.

Similarly, a bottom open end 222 may be joined to the center tube 206axially opposite the top open end 220 disposed along the longitudinalaxis 216. As best seen in FIG. 3, the bottom open end 222 may define aradially outer surface 232, and a radially inner surface 234 that is incommunication with the central reservoir 204.

Looking at FIGS. 2 thru 4, a locking feature 236 may be disposedproximate to the bottom open end 222 of the center tube 206. The lockingfeature 236 may include an entrance slot 238 that is disposed on theradially inner surface 234 of the center tube 206 that extends axiallyupwardly from the bottom open end 222. This entrance slot is configuredto allow the center tube 206 to slide over the tab 322 of the pedestal300 alluded to earlier herein during assembly.

As best seen in FIG. 4, the locking feature 236 may further comprise aramp slot 240 that extends axially upwardly and circumferentiallycounterclockwise from the entrance slot 238 along a predetermineddirection 241. The ramp slot 240 is in communication with the entranceslot 238 so that as the tab 322 of the pedestal 300 moves upwardly inthe entrance slot 238 when the center tube 206 moves downwardly, the tab322 will eventually arrive at the ramp slot 240. Twisting the centertube 206 circumferentially will cause the center tube 206 to movedownwardly, impinging upon the filter seal 120 (e.g. see FIG. 3). Inother embodiments, this arrangement may be reversed such that the rampslot extends axially upwardly and circumferentially clockwise. In such acase, the center tube will need to be twisted in the opposite direction.

With continued reference to FIG. 4, the locking feature 236 may furthercomprise a circumferential locking slot 242 that extendscircumferentially counterclockwise from the ramp slot 240. Thecircumferential locking slot 242 is in communication with the ramp slot240, and terminates at a stop surface 244. Consequently, as the centertube 206 is twisted circumferentially, the axial position of the centertube is substantially fixed by the tab 322 of the pedestal 300. Again,this arrangement may be reversed such that the circumferential lockingslot extends in the clockwise direction, necessitating that the centertube be rotated in the opposite direction.

Continued twisting of the center tube 206 in the counterclockwisedirection will allow the tab 322 to contact or nearly contact the stopsurface 244, at which time the upward force exerted by the filter seal120 causes the center tube 206 to move slightly upwardly until the tab322 engages a detent notch 246 that extends axially downwardly from thecircumferential locking slot 242 being in communication therewith. Now,the center tube 206 is locked into position both axially, radially andcircumferentially against unintentional movement.

An angled surface 248 may extend from the detent notch 246 to the stopsurface 244, matching the shape of the tab 322. Hence, the angledsurface 248 may parallel to the predetermined direction 241 that theramp slot 240 extends. Likewise, the stop surface 244 may extend axiallyto match shape of the tab 322.

Other configurations are possible for these various features.

Looking at FIGS. 4 and 7, the center tube 206 has a necked downconfiguration at the bottom open end 222 including an enlarged bottomannular portion 248, a reduced top annular portion 250, and atransitional annular portion 252 therebetween. The entrance slot 238 isformed by the enlarged bottom annular portion 248, and the transitionalannular portion 252. The ramp slot 240 is formed by the transitionalannular portion 252, and the reduced top annular portion 250. Thecircumferential locking slot 242, and the detent notch 246 are formed bythe reduced top annular portion 250.

Again, other configurations for these features are possible in otherembodiments of the present disclosure.

Looking at FIG. 7, it can be seen that the center tube 206 (andtherefore the filter element 200), are constructed so that both ends aresimilarly or identically constructed. So, the center tube 206 may berotated about an axis that extends through axial midpoint of the centertube and perpendicular to the longitudinal axis 216 an amount of 180degrees and still be able to be installed with the pedestal 300. Thismay not be the case in other embodiments of the present disclosure. Insuch a case, the top locking feature may or may not be used to attachthe base to the center tube. An example, of the use of both top andbottom locking features in a canister filer system will be discussedlater herein.

The top portion of the entrance slot 238, and the entirety of the rampslot 240, the circumferential locking slot 242, and detent notch 246extend completely radially through the center tube 206. On the otherhand, the lower portion of the entrance slot 238 does not extendcompletely radially through the center tube 206 (denoted by dottedlines). Thus, a side action may form the thru-portions of these featureswhile a bottom core may form the blind portion of the entrance slot andcontacts the side action. So, the center tube may be manufactured usinga thermoplastic injection molding process. A nylon, a polyurethane, orany other suitable material may be used to form the center tube.

Other configurations for these features may be employed to facilitatethe use of other manufacturing processes, etc.

Next, a pedestal 300 that may be used with a canister filter system 100,and a filter element 200 for positioning and retaining the filterelement 200 in the canister filter system 100 will now be discussed withreference to FIGS. 4 and 5.

The pedestal 300 may comprise an at least partially annular body 302defining a longitudinal axis 306, a radial direction 308, and acircumferential direction 310.

The body 302 may include a top annular portion 312 terminating at a topfree end 314 as earlier described herein. A tab 322 extends radiallyfrom the top annular portion, 312. The tab 322 includes a first axialsurface 328, a bottom circumferential surface 330, and a bottom rampsurface 332 extending from the bottom circumferential surface 330. Thefirst axial surface 328 is configured to engage a surface of theentrance slot 238, the bottom circumferential surface 330 is configuredto engage a surface of the circumferential locking slot 242, and thebottom ramp surface 332 is configured to engage a surface of the rampslot 240 of the center tube 206 as previously described herein.

In addition, the tab 322 further comprises a top ramp surface 334extending from the first axial surface 328 that is parallel to thebottom ramp surface 332 for engaging another surface of the ramp slot240. A top circumferential surface 336 extends from the top ramp surface334 that engages another surface of the circumferential locking slot242. A second axial surface 338 connects the bottom ramp surface 332 tothe top circumferential surface 336, and is configured to engage thestop surface 244 of the center tube 206.

The pedestal 300 may be complimentarily shaped to the bottom open end222 of the center tube 206. Consequently as seen in FIG. 5, the pedestal300 may have a bottom annular portion 318 that defines a bottom diameter320, and a top annular portion 312 that defines a top diameter 316 thatis less than the bottom diameter 320. Also, a flared annular portion 324(may also be referred to as a funnel annular portion) connects the topannular portion 312 to the bottom annular portion 318.

The pedestal 300 may further comprise a canister portion 340 (e.g. maybe attached thereto) and may include an annular outer wall 342 definingan outer diameter 344 that is greater than the bottom diameter 320 ofthe bottom annular portion 318 to form the annular cavity 118 (see FIG.1). As best seen in FIG. 5, a support wall 346 that is configured tosupport the bottom annular portion 318, and a funnel wall 348 connectingthe annular outer wall 342 to the support wall 346.

Looking at FIGS. 1, 7 and 8, it may be understood that the canisterfilter system 100 and its center tube 206 may be modified so that thecenter tube 206 has both top and bottom locking features for attachingboth the base 102 and the canister 104 to the filter element 200. Asshown in FIG. 8, a top pedestal 300 may be provided that is identicallyconfigured to that of FIG. 5 except that it has been rotated 180 degreesabout an axis passing through the axial midpoint of the center tube 206and that is perpendicular to the longitudinal axis 216 of the centertube 206 so that the top pedestal 300 may be operatively associated withthe base 102 instead of the canister 104 (e.g. attached to the baseinstead of the canister as previously described herein).

In FIG. 8, a bottom pedestal 300′ may be provided that includes an atleast partially annular body 302′ defining a longitudinal axis 306′, aradial direction 308′, and a circumferential direction 310′ that aredefined the same way as those of the top pedestal 300.

The bottom pedestal 300′ may include a top annular portion 312′ thatterminates at a top free end (not clearly shown but understood to besimilar to what has been previously described for pedestal 300 or whatis shown in FIG. 1), and that defines a top diameter (not clearly shownbut understood to be similar to what has been previously described forpedestal 300 or what is shown in FIG. 1). Likewise, the bottom pedestal300′ may also include a bottom annular portion 318′ defining a bottomdiameter (not clearly shown but understood to be similar to what hasbeen previously described for pedestal 300 or what is shown in FIG. 1)that is greater than the top diameter 316′. A flared annular portion324′ that connects the top annular portion 312′ to the bottom annularportion 318′. Also, a bottom tab 322′ extends radially from the topannular portion 312′.

The bottom annular portion 318′ may define at least one thru-slot (notclearly shown but understood to be similar to what has been previouslydescribed for pedestal 300) that extends radially and possibly axiallydownwardly through the bottom annular portion 318′ similar to pedestal300 as previously described earlier herein. It is to be understood thatthe pedestal 300 may be substituted for the bottom pedestal 300′ shownin FIG. 8 in some embodiments.

For example in FIGS. 1, 2 and 3, it is to be understood that thecanister 104 may comprise an outer annular wall 124 that defines anouter diameter 126 that is greater than the bottom diameter of thebottom pedestal 300′ (shown in FIG. 8). A support wall 346 would supportthe bottom annular portion 318′ of the bottom pedestal 300′, and anarcuate wall 130 would connect the support wall 346 to the outer annularwall 124.

As best seen in FIGS. 2 and 3, the filter seal 120 would contact thearcuate wall 130, forming a drain reservoir 132. Moreover, the bottomopen end 222 of the modified center tube 206 would impinge upon thefilter seal 120, creating a fluid tight seal between center tube 206 andthe filter seal 120, and another fluid tight seal between the filterseal 120 and the arcuate wall 130. The arcuate wall may have anothershape such as conical, etc. The filter seal may be omitted in someembodiments such as when the canister has a bottom closed end, etc.

Referring back to FIG. 8, the center tube 206′ includes a bottom lockingslot 224′ that extends axially from the bottom open end 222′ of thecenter tube 206 an axial distance 226′, and then extendscircumferentially a circumferential distance 228′. The center tube 206′may also have a top locking slot 224″ that extends axially from the topopen end 220′ of the center tube 206′ another axial distance 226″, andthen extends circumferentially in the opposite direction as compared tothe bottom locking slot 224′.

Furthermore, the center tube 206′ may define an inner diameter (notclearly shown but understood to be similar to what has been previouslydescribed for pedestal 300 or what is shown in FIG. 1) that is slightlygreater than the top diameter of the bottom pedestal 300′ that isdisposed within the inner diameter of the center tube 206′. The bottomtab 322′ of the bottom pedestal 300′ is disposed in the bottom lockingslot 224′ and is configured to guide the movement of the center tube206′. Also, the top pedestal 300 may define a diameter (e.g. 316) thatis slightly less than the inner diameter of the center tube 206′, andthat is disposed within the inner diameter of the center tube 206′. Thetop tab 322 of the top pedestal 300 may be differently configured thanthe bottom tab 322′ of the bottom pedestal 300′, and the top tab 322 maybe disposed in the top locking slot 224″ to guide the movement of thebase.

With continued reference to FIG. 8, a filter element with a center tube206′ having both top and bottom locking features that may be used withthe filter canister system just described will now be discussed. It isto be understood that the center tube 206′ shown in FIG. 8 is simplifiedto show the use of top and bottom locking features simultaneously. Inactuality, the middle portion of the center tube 206′ would haveperforations similar to what is shown in FIG. 7.

As alluded to earlier herein, the center tube 206′ may have a bottomopen end 222′ that is joined to the center tube 206′ opposite the topopen end 220′, both of which are disposed along the longitudinal axis306′. The bottom open end 222′ may define a radially outer surface 232′,and a radially inner surface that is in communication with the centralreservoir (not clearly shown in FIG. 8).

A first locking feature 236′ may be disposed proximate to the bottomopen end 222′. The first locking feature 236′ may include a firstentrance slot 238′ that is disposed on the radially inner surface (notclearly shown in FIG. 8) of the center tube 206′ extending axiallyupwardly from the bottom open end 222′. A first ramp slot 240′ mayextend axially upwardly and circumferentially counterclockwise from thefirst entrance slot 238′ along a first predetermined direction 241′, thefirst ramp slot 240′ being in communication with the first entrance slot238′. The entry slot may be axially tapered to provide a lead-in duringassembly.

Similarly, a second locking feature 236″ may be disposed proximate tothe top open end 220′. The second locking feature 236″ may include asecond entrance slot 238″ that is disposed on the radially inner surface(not clearly shown in FIG. 8) of the center tube 206′ extending axiallydownwardly from the top open end 220′. A second ramp slot 240″ mayextend axially downwardly and circumferentially clockwise from thesecond entrance slot 238″ along a second predetermined direction 241″,the second ramp slot 240″ being in communication with the secondentrance slot 238″.

As shown in FIG. 8, the first predetermined direction 241′ and thesecond predetermined direction 241″ are parallel to each other. Forexample, this may be true when the first locking feature 236′ isidentically configured as the second locking feature 236″ when rotatedabout an axis that is perpendicular to the longitudinal axis 306′ anamount of 180 degrees, and then aligned axially and circumferentiallywith the second locking feature 236″. This may not be the case for otherembodiments of the present disclosure.

The first locking feature may further comprise a first circumferentiallocking slot 242′ extending circumferentially counterclockwise from thefirst ramp slot 240′, the first circumferential locking slot 242′ beingin communication with the first ramp slot 240′ and terminating at afirst sloping surface 254 that extends axially upwardly andcircumferentially counterclockwise.

Similarly, the second locking feature 236″ may further comprise a secondcircumferential locking slot 242″ extending circumferentially clockwisefrom the second ramp slot 240″, the second circumferential locking slot242″ being in communication with the second ramp slot 240″, andterminating at a second sloping surface 254′ extending axiallydownwardly and circumferentially clockwise.

For the first locking feature 236′, a first detent notch 246′ may extendaxially upwardly from the first circumferential locking slot 242′ beingin communication therewith. Likewise for the second locking feature236″, a second detent notch 246″ may extend axially downwardly from thesecond circumferential locking slot 242″ being in communicationtherewith.

The first detent notch 246′ may terminate circumferentially at a firststop surface 244′ that extends axially upwardly from the first slopingsurface 254, and the second detent notch 246″ may terminatecircumferentially at a second stop surface 244″ that extends axiallydownwardly from the second sloping surface 254′.

Looking at FIG. 8, the center tube 206′ has a necked down configurationat the bottom open end 222′ including an enlarged bottom annular portion248′, a reduced top annular portion 250′, and a transitional annularportion 252′ therebetween. The entrance slot 238′ is formed by theenlarged bottom annular portion 248′, the transitional annular portion252′, and the reduced top annular portion 250′. The first ramp slot 240′is formed by the reduced top annular portion 250′. The firstcircumferential locking slot 242′, and the first detent notch 246′ areformed by the reduced top annular portion 250′. The top open end 220′have be similarly described, being mirrored about an axial midplane ofthe center tube 206′.

Referring to FIGS. 5 and 8, a pair of pedestals 300, 300′ that may beused with the filter element just described will be discussed in furtherdetail.

Each of the pair of pedestals 300, 300′ may comprise an at leastpartially annular body 300, 302′ defining a longitudinal axis 306, 306,a radial direction 308, 308′, and a circumferential direction 310, 310′.

Each may have a top annular portion 312, 312 terminating at a top freeend 314, and a tab 322, 322′ extending radially from the top annularportion 312, 312′. The tab 322, 322′ may include a first axial surface328, 328′, a bottom circumferential surface 330, 330′, and a bottom rampsurface 332, 332′ extending from the bottom circumferential surface 330,330′. As best seen in FIG. 8, the surface of one tab may be differentlyconfigured (e.g. have different dimensions) than the correspondingsurface of the other tab but not necessarily so.

Still looking at FIGS. 5 and 8, each tab 322, 322′ may further comprisea top ramp surface 334, 334′ extending from the first axial surface 328,328′ that is parallel to the bottom ramp surface 332, 332′, a topcircumferential surface 336, 336′ extending from the top ramp surface334, 334′, and a second axial surface 338, 338′ connecting the bottomramp surface 332, 332′ to the top circumferential surface 336, 336′.

Each pedestal 300, 300′ may further comprise a bottom annular portion318, 318′ that defines a bottom diameter 320, and the top annularportion 312, 312′ defines a top diameter 316 that is less than thebottom diameter 320. A flared annular portion 324, 324′ may connect thetop annular portion 312, 312′ to the bottom annular portion 320, 320′.

All of these various surfaces of one tab may be differently configuredthan the corresponding surfaces of the other tab. Hence, the tab of eachof the pair of pedestals may be differently configured.

As shown in FIG. 8, multiple locking features and tabs may be used atboth ends of the center tube 206′, but not necessarily so.

During installation for the embodiment in FIG. 8, the base and/or toppedestal is first attached to the center tube of the filter element. Thetop tab is prevented from entering the upper detent notch due to itsdimensions. Then, the base and filter element are attached to the bottompedestal until the bottom tab is seated in the lower detent notch sincethe bottom tab is smaller than the top tab.

Next, an interface for use with a filter system similar to thatdescribed earlier herein will be discussed with reference to FIGS. 9thru 11.

The interface 400 may comprise a filter element 200 that is configuredthe same as or similar to that as previously described herein. Thefilter element 200 may include a first open end 402 defining a firstlocking slot 404, and a second open end 406 defining a second lockingslot 408. A first pedestal 410 may be provided that includes a first tab412 that is disposed in the first locking slot 404. Similarly, a secondpedestal 414 may be provided including a second tab 416 that is disposedin the second locking slot 408. The second tab 416 may be differentlyconfigured as the first tab 412. Either tab may have any suitableconfiguration including rectangular, square, elliptical, circular,quadrilateral, etc.

In some embodiments, the first locking slot 404 may be identicallyconfigured as the second locking slot 408 when rotating the geometry ofthe first slot about an axis that is perpendicular to the longitudinalaxis 216 of the filter element 200 an amount of 180 degrees and thenaligning the first locking slot 404 with the second locking slot 408axially, circumferentially, and radially. This may not be the case inother embodiments of the present disclosure.

As illustrated in FIGS. 9 and 10, the first locking slot 404 may includea first detent notch 418 that defines an extremity 420 that is thefurthest axially from the first open end 402 of the filter element 200,and the first tab 412 may be configured to move axially into and out ofthe first detent notch 418.

As best seen in FIG. 11, the second locking slot 408 may include asecond detent notch 422 that defines an extremity 420′ that is furthestaxially from the second open end 406 of the filter element 200, and thesecond tab 416 may be configured to be prevented from moving into andout of the second detent notch 422.

To that end, FIGS. 10 and 11 show that the first tab 412 includes afirst bottom circumferential surface 424 defining a first bottomcircumferential surface width 426, and the second tab 416 includes asecond bottom circumferential surface 428 defining a second bottomcircumferential surface width 430 that is greater than the first bottomcircumferential surface width 424. The difference in these structuresalong with the necked throat of the entrance of the detent notches,formed by an axial throat surface 432 and a slanted throat surface 434,allows the first tab to enter the detent notch and not the second tab.

Also, the first tab 412 includes a first ramp surface 436 and a secondramp surface 438 that are parallel to each other and that define a firstramp width 440 that measured perpendicularly to the first ramp surface436. Likewise, the second tab 416 defines a third ramp surface 442 and afourth ramp surface 444 that are parallel to each other and that definea second ramp width 446 that is measured perpendicularly to the thirdramp surface 442 and the fourth ramp surface 444. The second ramp width446 may be greater than the first ramp width 440, blocking its entryinto the detent notch.

Accordingly, the first tab 412 may be configured to move axially (intothe entrance portion of the first locking slot 404), diagonally (alongthe ramp portion of the first locking slot 404), circumferentially (inthe circumferential portion of the first locking slot 404) and axiallyinto the first detent notch 418, while the second tab 416 is configuredto move axially, diagonally, and circumferentially in like manner as thefirst tab, except that the second tab 416 reaches a stop 448 (see FIG.11) in the second locking slot 408 before entering the second detentnotch 422. This may not be the case for other embodiments of the presentdisclosure.

Any of the aforementioned features may be varied in configuration to bedifferent in other embodiments of the present disclosure. In particular,the locking slot may follow any desirable path and may have differentlyconfigured walls that form them while the tabs may have any suitableconfiguration including round, polygonal, etc.

INDUSTRIAL APPLICABILITY

In practice, a filter element, a pedestal, or a canister filter systemaccording to any embodiment disclosed herein may be obtained or providedin an OEM (original equipment manufacturer) or aftermarket context. Thevarious features previously discussed may be used to both properlyorient, position, and lock the various components of the canister filtersystem into place.

The center tube and the pedestal may be made from any suitable materialincluding plastic, metal, etc. It may be desirable to choose materialsthat are chemically compatible with the fluids being filtered.

In previous designs, there may be a problem related to the attachment ofthe filter element to the housing (canister). Conventionally, theattachment of filter element to the housing, maintaining the properforce on the seal, and providing alignment of the filter element to thehousing may be difficult.

Various embodiments of the present disclosure allow a newly developedmethod to install the filter element to the housing. The filterinstallation helps to ensure the proper alignment of filter elementwithin the housing as well as maintaining the downward force on theseal. Further, the new design of filter element includes slots in thecenter tube that will allow tabs on the filter housing pedestal toengage. When the filter is rotated, it will provide locking of thefilter element with the housing and the required force to help ensurethe proper engagement of the seal with the housing base for theseparation of pure and impure water, etc. Moreover, the slots andpedestal tabs can be changed (in number, position, configuration, etc.)so that wrong filter is not used resulting in damage to machinecomponents.

More specifically, the tab of the lower pedestal engages thecorresponding locking slot of the center tube, providing downward forceto push bottom seal into place when the filter is rotated into housingat installation. Also, the position of the top seal is also provided sothat it will seal properly.

It is contemplated that other embodiments of the present disclosure maywork or be structured differently so not all of the benefits justdescribed may be obtained.

In some embodiments, the filter element/center tube may sit on top ofthe tab(s) at the bottom of the housing. In such a case, a proper sealmay be provided at the top end, but the user may have to provide theforce to overcome the seal at the bottom, etc.

It is further contemplated that the features of the pedestal includingthe tab may be swapped for the features of the center tube/filterelement including the locking feature/slot, etc. in other embodiments ofthe present disclosure.

In light of the foregoing, a method of assembly of a canister filtersystem according to an embodiment of the present application may beemployed as depicted in FIG. 12.

The method 500 may comprise inserting a first filter component into asecond filter component (step 502), and continuing the insertion until afirst tab of either the first filter component or the second filtercomponent contacts the other of the first filter component and thesecond filter component (step 504). For example, the filter element maybe inserted into a filter base or a canister (housing), etc. until thefilter element contacts the tab of the filter base or canister (or viceversa).

In particular embodiments, the first tab of either the first filtercomponent or the second filter component slides into a first slot of theother of the first filter component or the second filter component (step506).

Sometimes, the first tab slides upwardly in the first slot until thefirst tab reaches a ramp portion of the first slot (step 508, e.g. seeFIGS. 2 thru 4, 8).

Then, the first filter component or the second filter component may berotated, causing the first tab to slide along the ramp portion of thefirst slot until the first tab reaches a circumferential portion of thefirst slot, causing the first filter component or the second filtercomponent to contact a seal (step 510, e.g. see FIGS. 2 thru 4).

Next, the first filter component or the second filter component (orboth) may be rotated until the first tab reaches a stop or a detentnotch (step 512, e.g. see FIGS. 4, 10, and 12).

In some embodiments, the first tab slides upwardly or downwardly in thedetent notch (step 514, e.g. see FIGS. 4, 8, and 10).

In yet further embodiments, the method 500 may further comprisingattaching the first filter component or the second filter component to athird filter component, providing a seal (step 516, e.g. see FIG. 1which indicates the canister and the filter element may be attached tothe base to create one or more seals).

The method 500 may also include inserting a second tab of a third filtercomponent into a second slot of the first filter component or the secondfilter component until the second tab reaches a ramp portion of thesecond slot (step 518, e.g. see FIGS. 1, 8 thru 11).

In such a case, the method 500 may further comprising rotating the firstfilter component or the second filter component until the second tabslides along the ramp portion of the second slot, reaches acircumferential portion of the second slot, and continues until thesecond tab reaches a second stop or a second detent notch (step 520).

If a second detent notch is reached, then the second tab may slideupwardly or downwardly in the second detent notch (step 522).

Once assembled as best seen in FIG. 1 for some embodiments of thepresent disclosure, a bottom seal 140, an inner top seal 142, and anouter top seal 144 may be created to help prevent any fluid fromleaking.

It will be appreciated that the foregoing description provides examplesof the disclosed assembly and technique. However, it is contemplatedthat other implementations of the disclosure may differ in detail fromthe foregoing examples. All references to the disclosure or examplesthereof are intended to reference the particular example being discussedat that point and are not intended to imply any limitation as to thescope of the disclosure more generally. All language of distinction anddisparagement with respect to certain features is intended to indicate alack of preference for those features, but not to exclude such from thescope of the disclosure entirely unless otherwise indicated.

Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the embodiments of theapparatus and methods of assembly as discussed herein without departingfrom the scope or spirit of the invention(s). Other embodiments of thisdisclosure will be apparent to those skilled in the art fromconsideration of the specification and practice of the variousembodiments disclosed herein. For example, some of the equipment may beconstructed and function differently than what has been described hereinand certain steps of any method may be omitted, performed in an orderthat is different than what has been specifically mentioned or in somecases performed simultaneously or in sub-steps. Furthermore, variationsor modifications to certain aspects or features of various embodimentsmay be made to create further embodiments and features and aspects ofvarious embodiments may be added to or substituted for other features oraspects of other embodiments in order to provide still furtherembodiments.

Accordingly, this disclosure includes all modifications and equivalentsof the subject matter recited in the claims appended hereto as permittedby applicable law. Moreover, any combination of the above-describedelements in all possible variations thereof is encompassed by thedisclosure unless otherwise indicated herein or otherwise clearlycontradicted by context.

What is claimed is:
 1. A pair of pedestals for use with a canisterfilter system and a filter element, wherein each of the pair ofpedestals comprise: an at least partially annular body defining alongitudinal axis, a radial direction, and a circumferential direction,and including a top annular portion terminating at a top free end; and atab extending radially from the top annular portion, the tab including afirst axial surface, a bottom circumferential surface, and a bottom rampsurface extending from the bottom circumferential surface.
 2. The pairof pedestals of claim 1 wherein the tab further comprises a top rampsurface extending from the first axial surface that is parallel to thebottom ramp surface, a top circumferential surface extending from thetop ramp surface, and a second axial surface connecting the bottom rampsurface to the top circumferential surface.
 3. The pair of pedestals ofclaim 1 wherein each of the pair of pedestals further comprise a bottomannular portion that defines a bottom diameter, and wherein the topannular portion defines a top diameter that is less than the bottomdiameter.
 4. The pair pedestals of claim 3 wherein each of the pair ofpedestals further comprises a flared annular portion that connects thetop annular portion to the bottom annular portion.
 5. The pair ofpedestals of claim 2 wherein the tab of each of the pair of pedestalsare differently configured.
 6. A canister filter system comprising: afilter element that includes at least partially a cylindricalconfiguration and that defines a longitudinal axis, and a radialdirection, the filter element comprising: an annular filter mediadefining a central passage; a center tube that is disposed in thecentral passage of the annular filter media that defines a centralreservoir, and the annular filter media surrounds the center tube andthe central reservoir; a top open end joined to the center tube disposedalong the longitudinal axis, the top open end including an openingallowing fluid to flow from the central reservoir to the outside of thefilter element; and a bottom open end joined to the center tube oppositethe top open end disposed along the longitudinal axis: a canister thatincludes a top open end, and a bottom closed end or a bottom open enddisposed along the longitudinal axis; a base that is configured to beattached to the canister; a bottom pedestal including an at leastpartially annular body defining a longitudinal axis, a radial direction,and a circumferential direction; a top annular portion terminating at atop free end and defining a top diameter; a bottom annular portiondefining a bottom diameter that is greater than the top diameter; and abottom tab extending radially from the top annular portion; and whereinthe bottom pedestal rests on the bottom closed end of the canister, andthe filter seal is disposed below the tab of the bottom pedestal andaround the bottom annular portion while contacting the canister; and atop pedestal comprising a top tab, the top pedestal being operativelyassociated with the base.
 7. The canister filter system of claim 6wherein the bottom pedestal includes a flared annular portion thatconnects the top annular portion to the bottom annular portion.
 8. Thecanister filter system of claim 6 wherein the bottom annular portion isattached to the canister and the top pedestal is attached to the base.9. The canister filter system of claim 6 wherein the bottom annularportion defines at least one thru-slot that extends radially and axiallydownwardly through the bottom annular portion.
 10. The canister filtersystem of claim 6 wherein the canister comprises an outer annular wallthat defines an outer diameter that is greater than the bottom diameterof the bottom pedestal, a support wall that is configured to support thebottom annular portion of the pedestal, and an arcuate wall thatconnects the support wall to the outer annular wall.
 11. The canisterfilter system of claim 10 further comprising a filter seal defining anaperture that is configured to mate with the bottom annular portion,wherein the filter seal contacts the arcuate wall, forming a drainreservoir.
 12. The canister filter system of claim 11 wherein the bottomopen end of the center tube impinges upon the filter seal, creating afluid tight seal between center tube and the filter seal, and anotherfluid tight seal between the filter seal and the arcuate wall.
 13. Thecanister filter system of claim 12 wherein the center tube includes abottom locking slot that extends axially from the bottom open end of thecenter tube an axial distance, and then extends circumferentially acircumferential distance, and a top locking slot that extends axiallyfrom the top open end of the center tube another axial distance, andthen extends circumferentially in the opposite direction as compared tothe bottom locking slot.
 14. The canister filter system of claim 13wherein the center tube defines an inner diameter that is slightlygreater than the top diameter of the bottom pedestal that is disposedwithin the inner diameter, and the bottom tab of the bottom pedestal isdisposed in the bottom locking slot and is configured to guide themovement of the center tube, and the top pedestal defines a diameterthat is slightly less than the inner diameter of the center tube and isdisposed within the inner diameter, the top tab of the top pedestal isdifferently configured than the bottom tab of the bottom pedestal, andthe top tab is disposed in the top locking slot and is configured toguide the movement of the base.